1. Field of the Invention
The present invention relates to a probe assembly for lapping a bar, an apparatus for lapping a bar and a method for lapping a bar, and more particularly, to the structure of a probe assembly.
2. Description of the Conventional Art
When a bar that is provided with a plurality of elements to be formed into sliders is lapped in the process of manufacturing thin-film magnetic heads, it is significantly important to precisely control the amount in which a read element (MR element) is lapped. For this purpose, a technique is known in which a resistive film called an RLG (Resistance Lapping Guide) sensor is provided on a surface to be lapped of a bar and in which the bar is lapped while measuring electrical resistance of the resistive film via electrode pads connected to the resistive film and monitoring it by means of an external control apparatus. The RLG sensor and the electrode pads for measuring the electrical resistance are typically formed in a dicing zone of a bar.
As a method for connection with the electrode pad, a technique to bond a wire to the electrode pad is known. However, this method is disadvantageous in that the electrode pad may be damaged when a wire is attached to or removed from the pad or may be damaged through electrostatic discharge. In addition, operation to remove a wire takes time and may lead to a longer lead time. Furthermore, part of a wire may remain on a bar when it is removed, causing contamination of a slider.
Therefore, alternative methods for connection with the electrode pad other than the wire bonding have been studied. Japanese Patent Laid-Open Publication No. 2000-163719 discloses a technique to press a needle-shaped terminal against an electrode pad. Japanese Patent Laid-Open Publication No. 95572/90 discloses a technique to press a probe against an electrode pad from behind.
The technique described in Japanese Patent Laid-Open Publication No. 2000-163719 is disadvantageous in that the needle is easily bent because of axial force applied thereto and, consequently leading to difficulty in positioning the needle. The technique described in Japanese Patent Laid-Open Publication No. 95572/90 is disadvantageous in that it requires a large apparatus and resultantly, higher cost. This technique is also disadvantageous in that excessive pressing force is easily applied to the pad because the probe is pressed against the bar while it faces the bar, and precise position control is required.